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Finding the Fourth Proportional to 686.12, 946.86 and 391.38

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Solution

The fourth proportional to 686.12, 946.86 and 391.38 is: 540.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.12 : 946.86 = 391.38 : x
  2. Step 2: Convert to fraction form
    686.12/946.86 = 391.38/x
  3. Step 3: Cross multiply
    686.12x = 946.86 × 391.38
  4. Step 4: Simplify right side
    686.12x = 370,582.07
  5. Step 5: Solve for x
    x = 370,582.07/686.12
  6. Step 6: Final answer
    x = 540.11

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Half scale
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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.